Method and apparatus for treating filaments



Nov. n'1939.

w. P. zABEL 2.179.367

METHOD AND APPARATUS FOR TREATING FILAMENTS Filed March 50, 1937 l l l l 66 66" 72 y F125. '7 90 /2 2, I sa ..7 './7 Q/82 52 f lo.: w 83 l 22 88 3/ 6/ u 4 g /52 5o e, 95 96 66 l 49 l M L l /00 4.5- :75 /0404 as I Z 63`- J7 53 "1W a 4 l` 29 ,i /s l l lK i i n I l f5 /2 l l $0 l w' `5--7 l I 52 .Q4- 6/ l es 60 ,0, es i i! /9 6 l @L l ,o wwwa..

l l 67 ll, I l

l l l .9.2 2 l ,8 2 48 n; I. 2 9 mgl. 4;/ .K s 4,

5 2 `2 37 23 nsQ 93 38 49 5 l 94 v l O l 4 3 O A l so i `l as Inventor; William l@ Zabel,

Patented Nov. 7, 1939 PATENT OFFICE IVIETHOD AND APPARATUS-FOR TREATING FILAMENTS William P. Zabel, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application lMarcl1.30, 1937, Serial No. 133,854

9 Claims.

My invention relates to a method and apparatus for heat treating filaments for incandescent lamps and the like and more particularly to a method and apparatus for heat treating single and multiple coil filaments separately at high temperatures for a relatively short interval of time.

Prior to my invention, most coiled filaments were heat treated while still joined together in a continuous thread, by passing said thread through a furnace at such a rate as to provide the desired amount of treatment. Such a method of operation requires that the mandrel be left in the lament coils as otherwise considerable unwinding and distortion results. This filament combination is objectionable since the coiling process used to produce it is not entirely satisfactory and because the heat treatment thereof is affected by the increase in mass produced by the mandrels. The effect of the additional mass is particularly noticeable where multiple coil filaments having a mandrel of larger size than usual are being treated. In other instances the coiled filaments are heat treated on mandrels after being severed yto length and are piled in a receptacle or boat of considerable size and heat capacity which is then inserted into a furnace. In this latter case, the mass of the boat, the mandrels and the pile of laments interferes with the uniform heating and cooling of each of the laments as well as retarding the free movement thereof.

My method and apparatus are featured principally by the heat treatment of the laments separately while supported by means of such extremely small mass as not to materially effect the time, rate or uniformity of heat treatment. Filaments treated by this method have all portions thereof raised very rapidly by the high temperature (1900-2300 C) of the heating means and, when removed from the heating means, cool very rapidly. In my apparatus a very thin receptacle, shaped so as to be ridged and at the same time hold one or more of the filaments separately, is heated by a resistance coil into which the receptacle is inserted for the period of -the treatment. As in all previous methods, the heating takes place in an inert or reducing gas. Because of the small .mass o'f the receptacle, the temperature of the treatment can be raised to a point limited only by the material of said receptacle which may be of tungsten if desired, and the time of treatment can be lowered so that the one-at-a-time or separated method of operation is commercially practical. When more than one filament is placed in the receptacle. each is placed in a separate groove or trough therein sulliciently distant from the other not to materially affect its rate of heating and cooling. The body of the lament does not increase in temperature to that of the heating means and, in one instance, is known to be 225 C. below said temperature. My apparatus provides additional means for assisting in the heat treatment comprising a plurality of receptacles, an endless chain for supportingV the receptacles mounted at intervals therealong, Aand means for indexing the chain to carry the receptacles to a loading position, into a hood lled with the inert gas. into operative relation to the electrically heated resistance coil and to an unloading position. Suitable means are also provided for cooling the apparatus and shielding portions thereof from the heat. Other features and advantages of my invention will be apparent from the detailed description which follows and from the accompanying drawing.

In the drawing, Fig. 1 is a perspective view of apparatus comprising my invention partially broken away to show some of the parts within the hood; Fig. 2 is a perspective. View on an enlarged scale of one of the filament transporting receptacles; Fig. 3 is a side elevation of a portion of my machine; and Figs. 4 and 5 are sections through the filament transporting receptacle and a modification thereof, respectively.

My apparatus as shown in Fig. l, comprises an endless chain II) having a plurality of receptacles or boats II mounted at regular intervals therealong for carrying single filaments up into the container or hood I2 and into operative relation to the heating coil I3. The chain Ill extends around the sprockets I4 and I5, which are rotatably mounted on pins I6 and I'I respectively, and is indexed periodically by rotation of sprocket I4. The support for pin I6 consists of post I8 extending upwardly from the block I9 on the table 20, and the support for pin I1 consists of the rod 2|, the lower end of which is attached to post I8 by bracket 22j. Disc 23 which is mounted on pin I6 adjacent y,'sprocket I4 supports a pin 24 which is pressed against the side of said sprocket I4 by leaf spring 25 and produces sufficient friction to hold the sprocket I4 and chain I0 in position between indexing movements.

The cycle of operation begins as a boat I I comes to rest before the guide 26 which is moved toward said boat until it parallels the far side thereof and surrounds the endgthereof. The guide 26 is provided to assist the operator in placing a filament 21 (Fig. 2) in the boat il and is so shaped as to allow the operator to rest the tweezers with which the filament 21 is picked up thereon. 'I'he guide 26 is mounted on the block 28 of insulating material which, in combination with the block 29, is clamped to the posts 3U and 3|. The posts 30 and 3| are each mounted by means of an insulating sleeve 32 on the slide 33 which is moved in the ways on table 20 formed by the bars 34 and 35 in order to carry the guide 26 into position. The slide is actuated by the cam 36 on the shaft 31 which engages the roller 38 on lever 39 which is connected to said slide 33 by the link 40. The lever39 pivots on a stud extending from bracket 4I and the roller 38 thereon is held against the cam 36 by the action of spring 42 which extends between posts in slide 33 and bar 34. The shaft 31 is supported by the bearing brackets 43 and 44 and is driven from cam shaft 45 through the f intermeshing gears 46 and 41. Shaft 31 and shaft 45 constitute the means for operating the apparatus and are driven from a source, preferable an electric motor and speed reducer (not shown), through a pulley 48 and belt, as shown 0n shaft 45, or through a gear and chain if more positive operation is desired.

Since the boats I I are of euch fragile construction and cannot strike the guide 26 without injury, the chain I0 adjacent the guide 26 is caused to pass between the guide rods 49 and 50 which hold it in position. Rod 49, as shown in Fig. 3, is mounted on the bracket 5| which is clamped on post I8, whereas rod 50 is held by an arm 52 of said bracket 5| which engages a stud extending from said rod 58. The lower end of the rod 50 is much wider than the remainder thereof in order to engage the links in the chain IIJ and is in two sections extending on both sides of the sprocket I4.

Once the filament 21 is placed in the boat II at the loading station, the guide 26 is moved away and the chain I8 is indexed suiiciently to bring the succeeding boat II thereon into Said position. The indexing movement, as shown in Fig. 3, is produced by mechanism operated by the cam 53 on the cam shaft 45 and engaging the studs 54 extending from the side of sprocket I4. The studs 54 lie in notches cut in the washer 55 separating sprocket I4 from post I8 and are engaged by the pawl 56. As the indexing takes place, the pawl 56 is moved down, catching one i of the studs 54 and turning the sprocket I4 counter-clockwise (Fig. 3). The pawl 56 is attached to the lever 51 which engages the cam 53 on shaft 45 through roller 58 and which pivots about the pin 59 extending from. bracket 68. The spring 6I extending' between the lever 51 and the post 62 on the table 20 holds the roller 58 in contact with the cam 53. Thewafher 55 causes the pawl 56 to slide up over the studs 54 on the retur movement of said pawl 56.

Repeated indexing carries the boats II up into the h'ood I2 which retains an inert or reducing atmosphere, preferably hydrogen, about the parts heated by the resistance coil I3 so as to protect themfrom oxidation. As shown in Fig. 1, the

hood I2 consists of a double-walled cylindrical container slidably mounted on the rods 63 and 64 and counterbalanced through cable 65 and other means (not shown). The rods 63 and 64 are engaged by brackets 66 attached to the top and bottom of the hood I2 and each carries a stop 61 clamped thereto against which thelower brackets 6'6 rest when said hood I2 is in position. The hood I2 can be moved up on the rods 63 and 64 for inSpection of the upper parts of similarly shaped trough cut from pin 14.

the apparatus. The cable 65 is attached to the bar 68 which is attached in turn to rods 69 at opposite sides of the hood I2 which engage the lower rim and top drum. thereof. The walls (top and side) of the hood I2, which are double, are' cooled by the circulation of water therebetween. The water is introduced through pipe and flexible hose 10 and is discharged through pipe and flexible hose 1I at a suciently rapid'rate to prevent it from raising above 25 to 35 C. The inert gas is introduced into the hood I2 through the pipe and flexible hose 12 the former of which passes through both walls thereof and extends upward therein to a position near the top. In this particular instance hydrogen flowing at the rate of '1 to 8'cu. it. per hour is introduced into the hood since it is a relatively good heat conductor and assists in removing the heat from the boats II and lament coils 21 after the heat treatment.

The chain `Il) carrying the boat I I finally passes onto the sprocket I5 whereupon it changes direction of movement and the boat I I is carried into axial alignment with the heating coil I3. During this movement the boat II retains its upright position on its mounting due to the weight 13 which causes it to turn with respect to the chain so that the filament is not ejected therefrom. As shown in Fig. 2, the boats I I are made from very thin material and are mounted at one end in a The boats II are fastened to pin 14 by a block 15 which is forced down into the interior of boat II by the screw 16. The screw 16 is threaded into the weight 13 and is also used to fasten Said weight 13 and pin 14 together. The pin 14 is mounted in an aperture in the block 11 which is attached to a tongue extending sideward from one of the links of the chain I0 and is free to turn as desired although restrained from slipping from the aperture by the spring 18 which engages a reduced section of the'pin 14. The spring 18 extends around one half of block 11 and through a slot therein which allows it to enter into the desired section of the pin 14.

The heat treatment occurs as the .resistance coil I3, which is retained at the desired temperature, is moved longitudinally so that the coils thereof encircle the boat II. The heating of the boat II and the filament 21 therein to the treating temperature is very rapid because yof the extremely small mass of these bodies. vThe boats I I are from .002 to .003 inch thick and are shaped, in this instance as shown in Fig. 4, in V form with small upstanding lips at both sides for holding the laments 21 more securely. The complete boats II including the portion thereof held by the apparatus weigh only 0.3 of a gram whereas the 60 watt filament coil and its single mandrel weigh .025 gram. The mandrel in the filament coil 21 weighs only .008 gram. In this combination the boats II are only 12 times as heavy as the filament and mandrel and are but 6 times as heavy as a 100 watt filament which weighs .052 gram. The particular boats II shown are formed from a ribbon of tungsten 1.78 inches long and 183 inch wide. A modiled boat II is shown in Fig. 5 which provides a. plurality of well'separated grooves for holding single la.- ments 21 so that more than one can be treated at a time. Each of the boats II and II provides a groove or trough which holds the filament coil 21 straight and prevents axial distortion during treatment. Since it is very important that the boats II do not distort and contact the resistance coil I3 and do not contaminate the filament 21, which is of tungsten, said boats I are preferably made from tungsten having the same properties as the socalled non-sag filaments used in lamps and produced according to the Paez Patent 1,410.499 of March 21, 1922. The resistance coil I3, in this instance, is also preferably of tungsten since it resists distortion better at the high temperature of the treatment than other materials, and has a 15g inch opening therein in which to accommodate the boat which is of 1/8 inch maximum section. The resistance' coil I3 is supported at its ends which are attached to respective posts 30 and 3| and by the support wires 19 and 80 which have notched ends in each of which one turn f the coil rests. The ends of the resistance coil I3 are in each case clamped to their respective posts by a block 8| which is forced thereagainst by the screw 82 threaded in the band 83 encircling the post. The upper ends of the posts 30 and 3| adjacent the resistance coil I3 are held in position by the insulating blocks 84 and 85 which are clamped thereto by the bolt 86 passing therethrough. The support Wires 19 and 80 are em 'bedded in an insulating block 81 which is supported by a Wire 88 extending from the insulating block B to said block 81. In order to protect the chain I0 and the other mechanism from heat radiated by the resistance coil I3, the shield 89 is introduced which is fastened to post 30 and is apertured for the resistance coil I3. The posts 3|! and 3|, as shown, extend downward between the insulating blocks 28 and 29 and into the insulating sleeves 32 in the slide 33. The electric current required to heat the resistance coil I3 is carried thereto from a source (not shown) through the posts 30 and 3| which are each connected to said source through a cable 90 and clamp 9|. An insulating guard 92 attached to block 28 prevents the operator from accidentally touching the posts 30 and 3| at a point adjacent the loading station. The longitudinal movement of the resistance coil I3 is caused by movement of the posts 38 and 3| which carry the guide 2S into positionv with the same motion, as alreadyf described. Heat resisting windows may be placed in the hood I2 for viewing the treatment and through which an optical pyrometer may be sighted to measure the temperature thereof. During one treatment in 'which filaments 21 for lamps in general home and business use are being treated the resistance coil I3 is kept at 2100 C. The temperature of the treatment can not be measured absolutely satisfactorily because of the diiiculty of achieving black body conditions. Experiments have therefore been conducted in which substances such as highly purified platinum and A1203, having a known melting point within the temperature range of the heat treatment, are melted in the boats while the temperature of the resistance coil I3 is measured optically. Platinum, which melts at 1755 C., was caused to melt when the resistance coil was at 1980 C. whereas A1203 which melts at 2050 C. was caused to melt when the resistance coil was at 2275 C. so that it appears there is 225 C. difference between .the `boat and the filament coil 21 during the treatment. Normal treatment is for a period of less than 30 seconds although in the instance referred to only ve seconds is allowed to lapse before the resistance coil I3 is automatically moved away from the boat I i.

After treatment, the boat is indexed out of position and nally, after several more indexing movements, it passes down out of the mouth of the hood |2 and into an unloading station directly behind the loading station. At this location the boats are automatically tipped so that filaments 21 are dumped onto the chute 93 (Fig. 3) and slide down into the cup 94. The boats I are tipped by the leaf spring 95 which is mounted on the end of the chute 93 and is moved into engagement with the lower end of the weight 13 by the movement of the chute 93 to a position below the boat i The chute 93 is mounted on the arm 96 pivoted in the bracket 91 and is moved by engagement of the arm 98-extending from the lower end thereof with the pin 99 which is fastened to the cam shaft 45 by blocks |00 and moved thereby. The spring |0| extending between the arm 96 and the block |02 mounted on post 62 keeps the chute 93 back away from the chain I0 as far as permitted by the other mechanism. Once having pushed the weight 13 sideward as far as possible through the movement of chute 93, the end of the leaf spring 85 is raised to tip the boats even farther. as the pin 99 strikes the end of the finger |03 attached to a mid point of the spring 95 and causes This latter movement is produced said spring to be bent upwardly, Another finger long enough for the filament 21 to drop out.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. An apparatus for the heat treatment of y metal iilaments comprising a boat of exceedingly small mass and heat capacity of the order of .003 inch in thickness for holding a filament, heating means for raising the temperature of the boat and filament therein and means for retaining a non-oxidizing atmosphere vabout the boat and filament while they are heated.

2. An apparatus for the heat treatment of metal laments comprising a boat' of exceeding- Iy small mass and heat capacity of the order of .003 inch in thickness for holding a filament, a resistance coil heated tothe temperature of the treatment desired by the passage of electricity therethrough adapted to encircle the boat and filament therein and' means for retaining a nonoxidizing atmosphere about the boat,` the filament and the resistance coil for the duration oi the heat treatment.

3. An apparatus for the heat treatment, of metal filaments comprising heating means, means for retaining a non-oxidizing atmosphere about the heating means, a boat of exceedingly small mass and heat capacity of the order of .003 inch in thickness for holding a filament and means for causing the boat to be carried into the non-oxidizing atmosphere and to be located in operative relation to the heating means for an interval of time, for holding said boat in said non-oxidizing atmosphere and out of operative relation with the heating means for another interval of time while the boat and filament cool and for thereafter removing the boat and filament from the non-oxidizing atmosphere.

4. An apparatus for the heat treatment of metal filaments comprising heating means, a container for retaining a non-oxidizing atmosphere about the heating means, an endless chain extending into the said container, a boat of exceedingly smallmass and heat capacity of the order of .003 inch in thickness mounted on` said chain for holding a filament and means for moving the chain to cause the boat to advance into the said container within operative relation to the heating means and then, after an interval .of time, away Ifrom said heating means but still in the nonoxidizing atmosphere and nally to an unloading station where the lament is removed from the boat.

5. An apparatus for the heat treatment of metal filaments comprising heating means, a container for retaining a non-oxidizing atmosphere about the heating means, an endless chain extending into the said container, a relatively long boat of substantially V section and of exceedingly small mass and heat capacity having one end mounted ron said chain and adapted to hold a lament in the trough thereof and to turn about its longitudinal axis, a weightattached to said boat with the greater portion below the axis of the trough and adjacent the base of the V so that the boat is always held upright and the filament is kept from falling out, and means for moving the chain to advance the boat into the said container, within operative relation to the heating means and then, after an interval of time, away from said heating means but still in the nonoxidizing atmosphere and nally to an unloading station where the filament is removed from the boat. s

6. An apparatus for the heat treatment of metal filaments comprising heating means, a container for retaining a non-oxidizing atmosphere about the heating means, a boat of exceedingly small mass and heat capacity into which a filament is placed and means for causing the boat to be carried into the non-oxidizing atmosphere and to be located in operative relation to the heating means for an interval of time, means for moving the heating means into and out of position adjacent to the boat so that said boat and lament are heated thereby and means for holding said boat in said non-oxidizing atmosphere and out j of operative relation with the heating means for another interval of time while the boat and filament cool and for therafter removing the boat and lament from the non-oxi`dizing atmosphere.

7. An apparatus for the heat treatment of metal laments comprising heating means, a

double-walled hood surrounding the heating means for retaining a non-oxidizing gaseous atmosphere which is lighter than air about said heating means, means for introducing a cooling liquid into the space between the walls of the hood to cool it and for withdrawing said ud, a boat of exceedingly small mass and heat capacity for holding a lament and means for causing the boat to be carried into the said hood and to be located in operative relation to the heating means for an interval of time, for holding said boat in said non-oxidizing atmosphere and out of operative relation with the heating means for another interval of time while the boat and lament cool and for thereafter removing the boat and lament from the non-oxidizing atmosphere.

8. An apparatus for the heat treatment of helically coiled metal filaments comprising a troughshaped boat of exceedingly small mass and heat capacity for holding a filament with its ends unconned, a containerfor retaining a non-oxidizing atmosphere, heating means in said container, and means for carrying said boat into said container adjacent to the heating means therein and then away from said heating means to permit the boat and filament therein to cool in the nonoxidizing atmosphere in said container.

9. An apparatus for the heat treatment of helically coiled metal laments comprising a plurality of trough-shaped boats of exceedingly 4small mass and heat capacity for holding laments with their ends unconned, movable carrier means for supporting said boats in horizontally disposed spaced relationship, a container for retaining a non-oxidizing atmosphere surrounding at least a portion of said carrier means and the boats thereon, heating means in said Container adjacent to the path of travel of said boats, and means for actuating said carrier to cause the boats thereon to be moved successively into positon adjacent to said heating means and then away therefrom to permit the boats and the laments therein to cool in the non-oxidizing atmosphere in said container.

WILLIAM P. ZABEL. 

